Liquid crystal composition and liquid crystal display device

ABSTRACT

To provide a liquid crystal composition satisfying at least one of characteristics such as high maximum temperature of a nematic phase, low minimum temperature of the nematic phase, small viscosity, suitable optical anisotropy, large dielectric anisotropy, large specific resistance, high stability to ultraviolet light and heat, or to provide a liquid crystal composition having suitable balance regarding at least two of the characteristics; and to provide an AM device having short response time, large voltage holding ratio, large contrast ratio, long service life and so forth. The liquid crystal composition has a nematic phase and contains a specific compound having large dielectric anisotropy as a first component, may contain a specific compound having high maximum temperature or small viscosity as a second component and a specific compound having high maximum temperature or large dielectric anisotropy as a third component; and a liquid crystal display device including the liquid crystal composition.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a 371 application of an international PCT application serial no. PCT/JP2013/054479, filed on Feb. 22, 2013, which claims the priority benefit of Japan application no. 2012-084015, filed on Apr. 2, 2012. The entirety of each of the above-mentioned patent applications is hereby incorporated by reference herein and made a part of this specification.

TECHNICAL FIELD

The invention relates to a liquid crystal composition mainly suitable for use in an active matrix (AM) device and so forth, and an AM device and so forth including the composition. In particular, the invention relates to a liquid crystal composition having a positive dielectric anisotropy, and a device that includes the composition and has a mode such as a twisted nematic (TN) mode, an optically compensated bend (OCB) mode, an in-plane switching (IPS) mode, a fringe field switching (FFS) mode, a polymer sustained alignment (PSA) mode or a field induced photo-reactive alignment (FPA) mode.

BACKGROUND ART

In a liquid crystal display device, a classification based on an operating mode for liquid crystals includes phase change (PC), twisted nematic (TN), super twisted nematic (STN), electrically controlled birefringence (ECB), optically compensated bend (OCB), in-plane switching (IPS), vertical alignment (VA), fringe field switching (FFS), polymer sustained alignment (PSA) and field induced photo-reactive alignment (FPA) modes. A classification based on a driving mode in the device includes a passive matrix (PM) and an active matrix (AM). The PM is classified into static, multiplex and so forth, and the AM is classified into a thin film transistor (TFT), a metal insulator metal (MIM) and so forth. The TFT is further classified into amorphous silicon and polycrystal silicon. The latter is classified into a high temperature type and a low temperature type according to a production process. A classification based on a light source includes a reflective type utilizing natural light, a transmissive type utilizing backlight and a transflective type utilizing both the natural light and the backlight.

The devices include a liquid crystal composition having suitable characteristics. The liquid crystal composition has a nematic phase. In order to obtain an AM device having good general characteristics, general characteristics of the composition should be improved. Table 1 below summarizes a relationship of the general characteristics between two aspects. The general characteristics of the composition will be further described based on a commercially available AM device. A temperature range of the nematic phase relates to a temperature range in which the device can be used. A preferred maximum temperature of the nematic phase is about 70° C. or higher and a preferred minimum temperature of the nematic phase is about −10° C. or lower. Viscosity of the composition relates to a response time in the device. A short response time is preferred for displaying moving images on the device. Accordingly, a small viscosity in the composition is preferred. A small viscosity at a low temperature is further preferred. An elastic constant of the composition relates to contrast in the device. For increasing the contrast in the device, a large elastic constant in the composition is further preferred.

TABLE 1 General Characteristics of Composition and AM Device General Characteristics General Characteristics No. of Composition of AM Device 1 Wide temperature range of a Wide usable temperature range nematic phase 2 Small viscosity ¹⁾ Short response time 3 Suitable optical anisotropy Large contrast ratio 4 Large positive or negative Low threshold voltage and dielectric anisotropy small electric power consumption Large contrast ratio 5 Large specific resistance Large voltage holding ratio and large contrast ratio 6 High stability to ultraviolet Long service life light and heat 7 Large elastic constant Large contrast ratio and short response time ¹⁾ A liquid crystal composition can be injected into a liquid crystal cell in a shorter period of time.

An optical anisotropy of the composition relates to a contrast ratio in the device. A product (Δn×d) of the optical anisotropy (Δn) of the composition and a cell gap (d) in the device is designed so as to maximize the contrast ratio. A suitable value of the product depends on the type of the operating mode. In a device having a mode such as TN, a suitable value is about 0.45 micrometer. In the above case, a composition having a large optical anisotropy is preferred for a device having a small cell gap. A large dielectric anisotropy in the composition contributes to a low threshold voltage, a small electric power consumption and a large contrast ratio in the device. Accordingly, the large dielectric anisotropy is preferred. A large specific resistance in the composition contributes to a large voltage holding ratio and a large contrast ratio in the device. Accordingly, a composition having the large specific resistance at room temperature and also at a temperature close to the maximum temperature of the nematic phase in an initial stage is preferred. A composition having a large specific resistance at room temperature and also at a temperature close to the maximum temperature of the nematic phase even after the device has been used for a long period of time is preferred. Stability of the composition to ultraviolet light and heat relates to a service life of the liquid crystal display device. In the case where the stability is high, the device has a long service life. Such characteristics are preferred for an AM device for use in a liquid crystal projector, a liquid crystal television and so forth. A large elastic constant in the composition contributes to the large contrast ratio and a short response time in the device. Accordingly, the large elastic constant is preferred.

A composition having a positive dielectric anisotropy is used for an AM device having the TN mode. On the other hand, a composition having a negative dielectric anisotropy is used for an AM device having the VA mode. A composition having a positive or negative dielectric anisotropy is used for an AM device having the IPS mode or the FFS mode. A composition having a positive or negative dielectric anisotropy is used for an AM device having the PSA mode or the FPA mode. Examples of the liquid crystal composition having the positive dielectric anisotropy are disclosed in Patent literature No. 1 as described below.

REFERENCE LIST Patent Literature

Patent literature No. 1: WO 96/11897 A.

A desirable AM device has characteristics such as a wide temperature range in which a device can be used, a short response time, a large contrast ratio, a low threshold voltage, a large voltage holding ratio and a long service life. A shorter response time even by one millisecond is desirable. Thus, desirable characteristics of a composition include a high maximum temperature of a nematic phase, a low minimum temperature of the nematic phase, a small viscosity, a suitable optical anisotropy, a large dielectric anisotropy, a large specific resistance, a high stability to ultraviolet light, a high stability to heat and a large elastic constant.

SUMMARY OF INVENTION Technical Problem

One of the aims of the invention is to provide a liquid crystal composition satisfying at least one of characteristics such as a high maximum temperature of a nematic phase, a low minimum temperature of the nematic phase, a small viscosity, a suitable optical anisotropy, a large dielectric anisotropy, a large specific resistance, a high stability to ultraviolet light, a high stability to heat and a large elastic constant. Another aim is to provide a liquid crystal composition having a suitable balance regarding at least two of the characteristics. A further aim is to provide a liquid crystal display device including such a composition. An additional aim is to provide a composition having a suitable optical anisotropy, a large dielectric anisotropy, a high stability to ultraviolet light, a large elastic constant and so forth, and is to provide an AM device having a short response time, a large voltage holding ratio, a large contrast ratio, a long service life and so forth.

Solution to Problem

The invention concerns a liquid crystal composition that has a nematic phase and contains at least one compound selected from the group of compounds represented by formula (1) as a first component, and a liquid crystal display device including the composition:

wherein, R¹ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons; X¹, X², X³ and X⁴ are independently hydrogen or fluorine; Y¹ is fluorine, chlorine, trifluoromethyl or trifluoromethoxy; and Z¹ is a single bond, ethylene or carbonyloxy.

Advantageous Effects of Invention

An advantage of the invention is a liquid crystal composition satisfying at least one of characteristics such as a high maximum temperature of a nematic phase, a low minimum temperature of the nematic phase, a small viscosity, a suitable optical anisotropy, a large dielectric anisotropy, a large specific resistance, a high stability to ultraviolet light and a high stability to heat. One aspect of the invention is a liquid crystal composition having a suitable balance regarding at least two of the characteristics. Another aspect is a liquid crystal display device including such a composition. A further aspect is a composition having a suitable optical anisotropy, a large dielectric anisotropy, a high stability to ultraviolet light and so forth, and is an AM device having a short response time, a large voltage holding ratio, a large contrast ratio, a long service life and so forth.

DESCRIPTION OF EMBODIMENTS

Usage of terms herein is as described below. A liquid crystal composition or a liquid crystal display device according to the invention may be occasionally abbreviated as “composition” or “device,” respectively. The liquid crystal display device is a generic term for a liquid crystal display panel and a liquid crystal display module. “Liquid crystal compound” means a compound having a liquid crystal phase such as a nematic phase or a smectic phase, or a compound having no liquid crystal phase but being useful as a component of the composition. Such a useful compound has a six-membered ring such as 1,4-cyclohexylene and 1,4-phenylene, and a rod-like molecular structure. An optically active compound or a polymerizable compound may be occasionally added to the composition. Even in the case where the compounds are liquid crystalline, the compounds are classified as an additive herein. At least one compound selected from the group of compounds represented by formula (1) may be occasionally abbreviated as “compound (1).” “Compound (1)” means one compound or two or more compounds represented by formula (1). A same rule also applies to any other compound represented by any other formula. An expression “at least one” in the context of “replaced” means that not only a position but also the number may be selected without limitation.

A maximum temperature of the nematic phase may be occasionally abbreviated as “maximum temperature.” A minimum temperature of the nematic phase may be occasionally abbreviated as “minimum temperature.” An expression “having a large specific resistance” means that the composition has a large specific resistance at room temperature and also at a temperature close to the maximum temperature of the nematic phase in an initial stage, and that the composition has a large specific resistance at room temperature and also at a temperature close to the maximum temperature of the nematic phase even after the device has been used for a long period of time. An expression “having a large voltage holding ratio” means that the device has a large voltage holding ratio at room temperature and also at a temperature close to the maximum temperature of the nematic phase in an initial stage, and that the device has a large voltage holding ratio at room temperature and also at a temperature close to the maximum temperature of the nematic phase even after the device has been used for a long period of time. When characteristics such as an optical anisotropy are described, values obtained according to the measuring methods described in Examples will be used. A first component includes one compound or two or more compounds. “Ratio of the first component” is expressed in terms of weight percent (% by weight) of the first component based on the total weight of the liquid crystal composition. A ratio of a second component and so forth is expressed in a similar manner. A ratio of the additive mixed with the composition is expressed in terms of weight percent (% by weight) or weight parts per million (ppm) based on the total weight of the liquid crystal composition.

A symbol R¹ is used for a plurality of compounds in chemical formulas of component compounds. In two of arbitrary component compounds, a group to be selected by R¹ may be identical or different. In one case, for example, R¹ of compound (1) is ethyl and R¹ of compound (1-1) is ethyl. In another case, R¹ of compound (1) is ethyl and R¹ of compound (1-1) is propyl. A same rule also applies to a symbol X³, Y¹ or the like.

The invention includes the items described below.

Item 1. A liquid crystal composition having a nematic phase and containing at least one compound selected from the group of compounds represented by formula (1) as a first component:

wherein, R¹ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons; X¹, X², X³ and X⁴ are independently hydrogen or fluorine; Y¹ is fluorine, chlorine, trifluoromethyl or trifluoromethoxy; and Z¹ is a single bond, ethylene or carbonyloxy.

Item 2. The liquid crystal composition according to item 1, containing at least one compound selected from the group of compounds represented by formula (1-1) as the first component:

wherein, R¹ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons; X³ and X⁴ are independently hydrogen or fluorine; and Y¹ is fluorine, chlorine, trifluoromethyl or trifluoromethoxy.

Item 3. The liquid crystal composition according to item 1 or 2, wherein a ratio of the first component is in the range of 5% by weight to 30% by weight based on the total weight of the liquid crystal composition.

Item 4. The liquid crystal composition according to any one of items 1 to 3, further containing at least one compound selected from the group of compounds represented by formula (2) as a second component:

wherein, R² and R³ are independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12 carbons in which at least one of hydrogen is replaced by fluorine; ring A and ring B are independently 1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene or 2,5-difluoro-1,4-phenylene; Z² is independently a single bond, ethylene or carbonyloxy; and m is 1, 2 or 3.

Item 5. The liquid crystal composition according to item 4, containing at least one compound selected from group of compounds represented by formula (2-1) to formula (2-13) as the second component:

wherein, R² and R³ are independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12 carbons in which at least one of hydrogen is replaced by fluorine.

Item 6. The liquid crystal composition according to item 4 or 5, containing at least one compound selected from the group of compounds represented by formula (2-1) according to item 5 as the second component.

Item 7. The liquid crystal composition according to any one of items 4 to 6, containing at least one compound selected from the group of compounds represented by formula (2-5) according to item 5 as the second component.

Item 8. The liquid crystal composition according to any one of items 4 to 7, wherein a ratio of the second component is in the range of 10% by weight to 80% by weight based on the total weight of the liquid crystal composition.

Item 9. The liquid crystal composition according to any one of items 1 to 8, further containing at least one compound selected from the group of compounds represented by formula (3) as a third component:

wherein, R⁴ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons; ring C is independently 1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene, 3,5-difluoro-1,4-phenylene, pyrimidine-2,5-diyl, 1,3-dioxane-2,5-diyl or tetrahydropyran-2,5-diyl; X⁵ and X⁶ are independently hydrogen or fluorine; Y² is fluorine, chlorine, trifluoromethyl or trifluoromethoxy; Z³ is independently a single bond, ethylene, carbonyloxy or difluoromethyleneoxy; n is 1, 2 or 3; and ring C when n is 2 and at least one of Z³ is difluoromethyleneoxy is independently 1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene, 3,5-difluoro-1,4-phenylene, pyrimidine-2,5-diyl or tetrahydropyran-2,5-diyl.

Item 10. The liquid crystal composition according to item 9, containing at least one compound selected from the group of compounds represented by formula (3-1) to formula (3-16) as the third component:

wherein, R⁴ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons; X⁵ and X⁶ are independently hydrogen or fluorine; and Y² is fluorine, chlorine, trifluoromethyl or trifluoromethoxy.

Item 11. The liquid crystal composition according to item 9 or 10, containing at least one compound selected from the group of compounds represented by formula (3-3) according to item 10 as the third component.

Item 12. The liquid crystal composition according to any one of items 9 to 11, containing at least one compound selected from the group of compounds represented by formula (3-8) according to item 10 as the third component.

Item 13. The liquid crystal composition according to any one of items 9 to 12, containing at least one compound selected from the group of compounds represented by formula (3-9) according to item 10 as the third component.

Item 14. The liquid crystal composition according to any one of items 9 to 13, containing at least one compound selected from the group of compounds represented by formula (3-15) according to item 10 as the third component.

Item 15. The liquid crystal composition according to any one of items 9 to 14, wherein a ratio of the third component is in the range of 20% by weight to 80% by weight based on the total weight of the liquid crystal composition.

Item 16. The liquid crystal composition according to any one of items 1 to 15, wherein a maximum temperature of a nematic phase is 70° C. or higher, an optical anisotropy (25° C.) at a wavelength of 589 nanometers is 0.07 or more and a dielectric anisotropy (25° C.) at a frequency of 1 kHz is 2 or more.

Item 17. A liquid crystal display device including the liquid crystal composition according to any one of items 1 to 16.

Item 18. The liquid crystal display device according to item 17, wherein an operating mode in the liquid crystal display device is a TN mode, an ECB mode, an OCB mode, an IPS mode, a PSA mode or an FPA mode, and a driving mode in the liquid crystal display device is an active matrix mode.

Item 19. Use of the liquid crystal composition according to any one of items 1 to 16 in a liquid crystal display device.

The invention also includes the following items: (1) the composition, further containing an optically active compound; (2) the composition, further containing an additive such as an antioxidant, an ultraviolet light absorber, a defoaming agent, a polymerizable compound and a polymerization initiator; (3) an AM device including the composition; (4) a device including the composition, and having a TN, an ECB, an OCB, an IPS, a PSA or an FPA mode; (5) a transmissive device including the composition; (6) use of the composition as a composition having a nematic phase; and (7) use as an optically active composition by adding the optically active compound to the composition.

The composition of the invention will be described in the order described below. First, a constitution of the component compounds in the composition will be described. Second, main characteristics of the component compounds and main effects of the compounds on the composition will be described. Third, a combination of components in the composition, a preferred ratio of the component compounds and the basis thereof will be described. Fourth, a preferred embodiment of the component compounds will be described. Fifth, specific examples of the component compounds will be shown. Sixth, an additive that may be mixed with the composition will be described. Seventh, methods for synthesizing the component compounds will be described. Last, an application of the composition will be described.

First, the constitution of the component compounds in the composition will be described. The composition of the invention is classified into composition A and composition B. Composition A may further contain any other liquid crystal compound, the additive, an impurity or the like in addition to the liquid crystal compound selected from compound (1), compound (2) and compound (3). “Any other liquid crystal compound” means a liquid crystal compound different from compound (1), compound (2) and compound (3). Such a compound is mixed with the composition for the purpose of further adjusting the characteristics. The additive includes the optically active compound, the antioxidant, the ultraviolet light absorber, a dye, the defoaming agent, the polymerizable compound and the polymerization initiator. The impurity includes a compound mixed in a process such as preparation of the component compounds. Even in the case where the compound is liquid crystalline, the compound is classified as the impurity herein.

Composition B consists essentially of compounds selected from compound (1), compound (2) and compound (3). A term “essentially” means that the composition may contain the additive and the impurity, but does not contain any liquid crystal compound different from the compounds. Composition B has a smaller number of components than composition A has. Composition B is preferred to composition A in view of cost reduction. Composition A is preferred to composition B in view of possibility of further adjusting physical properties by mixing any other liquid crystal compound.

Second, the main characteristics of the component compounds and the main effects of the compounds on the characteristics of the composition will be described. The main characteristics of the component compounds are summarized in Table 2 on the basis of advantageous effects of the invention. In Table 2, a symbol L stands for “large” or “high,” a symbol M stands for “medium,” and a symbol S stands for “small” or “low.” The symbols L, M and S represent classification based on a qualitative comparison among the component compounds, and 0 (zero) means “a value is nearly zero.”

TABLE 2 Characteristics of Compounds Compounds (1) (2) (3) Maximum Temperature S S to L S to M Viscosity M S to M M to L Optical Anisotropy M S to L M to L Dielectric Anisotropy L 0 S to L Specific Resistance L L L

Upon mixing the component compounds with the composition, the main effects of the component compounds on the characteristics of the composition are as described below. Compound (1) increases the dielectric anisotropy. Compound (2) increases the maximum temperature or decreases the viscosity. Compound (3) increases the dielectric anisotropy and decreases the minimum temperature.

Third, the combination of components in the composition, the preferred ratio of the component compounds and the basis thereof will be described. The combination of components in the composition include a combination of the first component and the second component, a combination of the first component and the third component and a combination of the first component, the second component and the third component. A preferred combination of the components in the composition includes the combination of the first component, the second component and the third component.

A preferred ratio of the first component is about 5% by weight or more for increasing the dielectric anisotropy, and about 30% by weight or less for decreasing the minimum temperature. A further preferred ratio is in the range of about 5% by weight to about 20% by weight. A particularly preferred ratio is in the range of about 5% by weight to about 15% by weight.

A preferred ratio of the second component is about 10% by weight or more for increasing the maximum temperature or decreasing the viscosity, and about 80% or less for increasing the dielectric anisotropy. A further preferred ratio is in the range of about 15% by weight to about 75% by weight. A particularly preferred ratio is in the range of about 20% by weight to about 70% by weight.

A preferred ratio of the third component is about 20% by weight or more for increasing the dielectric anisotropy, and about 80% by weight or less for decreasing the minimum temperature. A further preferred ratio is in the range of about 25% by weight to about 80% by weight. A particularly preferred ratio is in the range of about 30% by weight to about 80% by weight.

Fourth, the preferred embodiment of the component compounds will be described. R¹ and R⁴ are independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons. Preferred R¹ or R⁴ is alkyl having 1 to 12 carbons for increasing the stability to ultraviolet light, or for increasing the stability to heat. R² and R³ are independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12 carbons in which at least one of hydrogen is replaced by fluorine. Preferred R² or R³ is alkenyl having 2 to 12 carbons for decreasing the viscosity, and alkyl having 1 to 12 carbons for increasing the stability to ultraviolet light, or for increasing the stability to heat.

Preferred alkyl is methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl or octyl. Further preferred alkyl is ethyl, propyl, butyl, pentyl or heptyl for decreasing the viscosity.

Preferred alkoxy is methoxy, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy or heptyloxy. Further preferred alkoxy is methoxy or ethoxy for decreasing the viscosity.

Preferred alkenyl is vinyl, 1-propenyl, 2-propenyl, 1-butenyl, 2-butenyl, 3-butenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl, 1-hexenyl, 2-hexenyl, 3-hexenyl, 4-hexenyl or 5-hexenyl. Further preferred alkenyl is vinyl, 1-propenyl, 3-butenyl or 3-pentenyl for decreasing the viscosity. A preferred configuration of —CH═CH— in the alkenyl depends on a position of a double bond. Trans is preferred for decreasing the viscosity in the alkenyl such as 1-propenyl, 1-butenyl, 1-pentenyl, 1-hexenyl, 3-pentenyl and 3-hexenyl. Cis is preferred in the alkenyl such as 2-butenyl, 2-pentenyl and 2-hexenyl.

Preferred examples of alkenyl in which at least one of hydrogen is replaced by fluorine include 2,2-difluorovinyl, 3,3-difluoro-2-propenyl, 4,4-difluoro-3-butenyl, 5,5-difluoro-4-pentenyl and 6,6-difluoro-5-hexenyl. Further preferred examples include 2,2-difluorovinyl and 4,4-difluoro-3-butenyl for decreasing the viscosity.

Alkyl does not include cyclic alkyl. Alkoxy does not include cyclic alkoxy. Alkenyl does not include cyclic alkenyl. With regard to a configuration of 1,4-cyclohexylene, trans is preferred to cis for increasing the maximum temperature.

Ring A and ring B are independently 1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene or 2,5-difluoro-1,4-phenylene, and two of arbitrary ring A when m is 2 or 3 may be identical or different. Preferred ring A or ring B is 1,4-cyclohexylene for decreasing the viscosity, and 1,4-phenylene for increasing the optical anisotropy.

Ring C is 1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene, 3,5-difluoro-1,4-phenylene, pyrimidine-2,5-diyl, 1,3-dioxane-2,5-diyl or tetrahydropyran-2,5-diyl, and ring C when n is 2 and at least one of Z³ is difluoromethyleneoxy is independently 1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene, 3,5-difluoro-1,4-phenylene, pyrimidine-2,5-diyl or tetrahydropyran-2,5-diyl. Two of arbitrary ring C when n is 2 or 3 may be identical or different. Preferred ring C is 1,4-cyclohexylene for increasing the maximum temperature, 1,4-phenylene for increasing the optical anisotropy and 3,5-difluoro-1,4-phenylene for increasing the dielectric anisotropy.

Then, “2-fluoro-1,4-phenylene” is represented by a ring in which a left-hand side is taken as 1-position, and “2-fluoro-1,4-phenylene” and “3-fluoro-1,4-phenylene” show that positions of fluorine are different.

Z¹ and Z² are independently a single bond, ethylene or carbonyloxy, and two of arbitrary Z² when m is 2 or 3 may be identical or different. Preferred Z¹ is a single bond for decreasing the viscosity. Preferred Z² is a single bond for decreasing the viscosity, and carbonyloxy for increasing the maximum temperature. Z³ is independently a single bond, ethylene, carbonyloxy or difluoromethyleneoxy, and two of arbitrary Z³ when n is 2 or 3 may be identical or different. Preferred Z³ is a single bond for decreasing the viscosity, and difluoromethyleneoxy for increasing the dielectric anisotropy.

X¹, X², X³, X⁴, X⁵ and X⁶ are independently hydrogen or fluorine. Preferred X¹, X², X³, X⁴, X⁵ or X⁶ is fluorine for increasing the dielectric anisotropy, and hydrogen for decreasing the viscosity.

Y¹ and Y² are independently fluorine, chlorine, trifluoromethyl or trifluoromethoxy. Preferred Y¹ is fluorine for decreasing the viscosity. Preferred Y² is fluorine for decreasing the viscosity, and chlorine for decreasing the minimum temperature.

Then, m is 1, 2 or 3. Preferred m is 1 for decreasing the viscosity, and 2 or 3 for increasing the maximum temperature. Then, n is 1, 2 or 3. Preferred n is 2 for decreasing the minimum temperature, and 3 for increasing the maximum temperature.

Fifth, the specific examples of the component compounds will be shown. In the preferred compounds described below, R⁵ is straight-chain alkyl having 1 to 12 carbons or straight-chain alkenyl having 2 to 12 carbons, R⁶ is straight-chain alkyl having 1 to 12 carbons, straight-chain alkoxy having 1 to 12 carbons or straight-chain alkenyl having 2 to 12 carbons.

Preferred compound (1) includes compound (1-1-1) and compound (1-1-2). Further preferred compound (1) is compound (1-1-1). Preferred compound (2) includes compound (2-1-1) to compound (2-13-1). Further preferred compound (2) includes (2-1-1) and compound (2-5-1). Particularly preferred compound (2) includes compound (2-1-1). Preferred compound (3) includes compound (3-1-1), compound (3-2-1), compound (3-3-1), compound (3-3-2), compound (3-4-1) to compound (3-8-1), compound (3-9-1), compound (3-9-2), compound (3-10-1) to compound (3-14-1), compound (3-15-1), compound (3-15-2) and compound (3-16-1). Further preferred compound (3) includes compound (3-2-1), compound (3-3-1), compound (3-4-1) to compound (3-6-1), compound (3-8-1), compound (3-9-1), compound (3-9-2), compound (3-15-1) and compound (3-15-2). Particularly preferred compound (3) includes compound (3-3-1), compound (3-8-1), compound (3-9-1) and compound (3-15-2).

Sixth, the additive that may be mixed with the composition will be described. Such an additive includes the optically active compound, the antioxidant, the ultraviolet light absorber, the dye, the defoaming agent, the polymerizable compound and the polymerization initiator. The optically active compound is mixed with the composition for the purpose of inducing a helical structure in liquid crystals to give a twist angle. Examples of such a compound include compound (4-1) to compound (4-5). A preferred ratio of the optically active compound is about 5% by weight or less. A further preferred ratio is in the range of about 0.01% by weight to about 2% by weight.

The antioxidant is mixed with the composition for the purpose of preventing a decrease in specific resistance caused by heating in air, or maintaining a large voltage holding ratio at room temperature and also at a temperature close to the maximum temperature of the nematic phase after the device has been used for a long period of time.

Preferred examples of the antioxidant include compound (5) where p is an integer from 1 to 9. In compound (5), preferred p is 1, 3, 5, 7 or 9. Further preferred p is 1 or 7. Compound (5) where p is 1 is effective in preventing a decrease in the specific resistance caused by heating in air because the compound (5) has a large volatility. Compound (5) where p is 7 is effective in maintaining a large voltage holding ratio at room temperature and also at a temperature close to the maximum temperature of the nematic phase even after the device has been used for a long period of time because the compound (5) has a small volatility. A preferred ratio of the antioxidant is about 50 ppm or more for achieving the effect thereof, and about 600 ppm or less for avoiding a decrease in the maximum temperature or avoiding an increase in the minimum temperature. A further preferred ratio is in the range of about 100 ppm to about 300 ppm.

Preferred examples of the ultraviolet light absorber include a benzophenone derivative, a benzoate derivative and a triazole derivative. A light stabilizer such as an amine having steric hindrance is also preferred. A preferred ratio of the ultraviolet light absorber or the stabilizer is about 50 ppm or more for achieving the effect thereof, and about 10,000 ppm or less for avoiding a decrease in the maximum temperature or avoiding an increase in the minimum temperature. A further preferred ratio is in the range of about 100 ppm to about 10,000 ppm.

A dichroic dye such as an azo dye or an anthraquinone dye is mixed with the composition to be adapted for a device having a guest host (GH) mode. A preferred ratio of the dye is in the range of about 0.01% by weight to about 10% by weight. The defoaming agent such as dimethyl silicone oil or methyl phenyl silicone oil is mixed with the composition for preventing foam formation. A preferred ratio of the defoaming agent is about 1 ppm or more for achieving the effect thereof, and about 1,000 ppm or less for avoiding a poor display. A further preferred ratio is in the range of about 1 ppm to about 500 ppm.

The polymerizable compound is mixed with the composition to be adapted for the device having the polymer sustained alignment (PSA) mode. Preferred examples of the polymerizable compound include a compound having a polymerizable group, such as an acrylate, a methacrylate, a vinyl compound, a vinyloxy compound, a propenyl ether, an epoxy compound (oxirane, oxetane) and a vinyl ketone. Particularly preferred examples include an acrylate derivative or a methacrylate derivative. Examples of such a compound include compound (6-1) to compound (6-9). A preferred ratio of the polymerizable compound is about 0.05% by weight or more for achieving the effect thereof, and about 10% by weight or less for avoiding a poor display. A further preferred ratio is in the range of about 0.1% by weight to about 2% by weight.

Here, R⁷, R⁸, R⁹ and R¹⁰ are independently acryloyl or methacryloyl, R¹¹ and R¹² are independently hydrogen, halogen or alkyl having 1 to 10 carbons, Z⁴, Z⁵, Z⁶ and Z⁷ are independently a single bond or alkylene having 1 to 12 carbons, at least one of —CH₂— may be replaced by —O— or —CH═CH—, and q, r and s are 0, 1 or 2.

The polymerizable compound is preferably polymerized by irradiation with ultraviolet light or the like in the presence of a suitable initiator such as a photopolymerization initiator. Suitable conditions for polymerization, suitable types of the initiator and suitable amounts thereof are known to a person skilled in the art and are described in literature. For example, Irgacure 651 (registered trademark; BASF), Irgacure 184 (registered trademark; BASF) or Darocur 1173 (registered trademark; BASF), each being a photopolymerization initiator, is suitable for radical polymerization. A preferred ratio of the photopolymerization initiator is in the range of about 0.1% by weight to about 5% by weight of the polymerizable compound, and a particularly preferred ratio is in the range of about 1% by weight to about 3% by weight.

Seventh, the methods for synthesizing the component compounds will be described. The compound (1) to compound (3) can be synthesized by a known method. Examples of synthetic methods will be shown. Compound (1-1-1) is prepared by the method described in JP 2004-352720 A. Compound (2-1-1) is prepared by the method described in JP S59-70624 A and JP S59-176221 A. Compound (2-5-1) is prepared by the method described in JP S57-165328 A and JP S59-176221 A. Compound (3-3-1), compound (3-6-1), compound (3-7-1) and compound (3-9-1) are prepared by the method described in JP H10-251186 A. Compound (3-11-1), compound (3-12-1) and compound (3-14-1) are prepared by the method described in JP H2-233626 A. The antioxidant is commercially available. A compound represented by formula (5) where p is 1 is available from Sigma-Aldrich Corporation. Compound (5) where p is 7 and so forth are prepared according to the method described in U.S. Pat. No. 3,660,505 B.

Any compounds whose synthetic methods are not described above can be prepared according to the methods described in books such as Organic Syntheses (John Wiley & Sons, Inc.), Organic Reactions (John Wiley & Sons, Inc.), Comprehensive Organic Synthesis (Pergamon Press) and New Experimental Chemistry Course (Shin Jikken Kagaku Koza in Japanese) (Maruzen Co., Ltd.). The composition is prepared according to a known method from the thus obtained compound. For example, the component compounds are mixed and dissolved in each other by heating.

Last, the application of the composition will be described. The composition of the invention mainly has a minimum temperature of about −10° C. or lower, a maximum temperature of about 70° C. or higher, and an optical anisotropy in the range of about 0.07 to about 0.20. The device including the composition has a large voltage holding ratio. The composition is suitable for use in the AM device. The composition is particularly suitable for use in a transmissive AM device. The composition having an optical anisotropy in the range of about 0.08 to about 0.25, and also the composition having an optical anisotropy in the range of about 0.10 to about 0.30 may be prepared by controlling the ratio of the component compounds or by mixing with any other liquid crystal compound. The composition can be used as the composition having the nematic phase and as the optically active composition by adding the optically active compound.

The composition can be used for the AM device. The composition can also be used for a PM device. The composition can be used for an AM device and a PM device having a mode such as PC, TN, STN, ECB, OCB, IPS, FFS, VA, PSA or FPA. Use for an AM device having the TN, OCB, IPS or FFS mode is particularly preferred. In an AM device having the IPS mode or FFS mode, alignment of liquid crystal molecules in a state in which no voltage is applied may be parallel or perpendicular to a panel substrate. The devices may be of a reflective type, a transmissive type or a transflective type. Use for the transmissive device is preferred. The composition can also be used for an amorphous silicon-TFT device or a polycrystal silicon-TFT device. The composition can also be used for a nematic curvilinear aligned phase (NCAP) device prepared by microencapsulating the composition, and for a polymer dispersed (PD) device in which a three-dimensional network-polymer is formed in the composition.

EXAMPLES

In order to evaluate characteristics of a composition and a compound to be contained in the composition, the composition and the compound were made a measurement object. When the measurement object was a composition, the composition was measured as a sample as was, and values obtained were described. When the measurement object was a compound, a sample for measurement was prepared by mixing the compound (15% by weight) with a base liquid crystal (85% by weight). Values of characteristics of the compound were calculated using values obtained by measurement, according to an extrapolation method: (extrapolated value)={(measured value of a sample for measurement)−0.85×(measured value of base liquid crystal)}/0.15. When a smectic phase (or crystals) precipitated at the ratio thereof at 25° C., a ratio of the compound to the base liquid crystals was changed step by step in the order of (10% by weight: 90% by weight), (5% by weight: 95% by weight) and (1% by weight: 99% by weight). Values of a maximum temperature, an optical anisotropy, viscosity and a dielectric anisotropy with regard to the compound were determined according to the extrapolation method.

Components of the base liquid crystal were as described below. The ratio of each component is expressed in terms of % by weight.

Characteristics were measured according to the methods described below. Most of the measurement methods are applied as described in the Standard of the Japan Electronics and Information Technology Industries Association (hereinafter, abbreviated as JEITA) (JEITA ED-2521B) discussed and established by JEITA, or modified thereon.

Maximum temperature of a nematic phase (NI; ° C.): A sample was placed on a hot plate in a melting point apparatus equipped with a polarizing microscope and was heated at a rate of 1° C. per minute. Temperature when a part of the sample began to change from a nematic phase to an isotropic liquid was measured. A maximum temperature range of the nematic phase may be occasionally abbreviated as “maximum temperature.”

Minimum temperature of a nematic phase (T_(c); ° C.): Samples each having a nematic phase were put in glass vials and kept in freezers at temperatures of 0° C., −10° C., −20° C., −30° C. and −40° C. for 10 days, and then liquid crystal phases were observed. For example, when the sample maintained the nematic phase at −20° C. and changed to a crystal or a smectic phase at −30° C., T_(c) was expressed as T_(c)<−20° C. A minimum temperature of the nematic phase may be occasionally abbreviated as “minimum temperature.”

Viscosity (bulk viscosity; η; measured at 20° C.; mPa·s): A cone-plate (E type) rotational viscometer was used for measurement.

Viscosity (rotational viscosity; γ1; measured at 25° C.; mPa·s): Measurement was carried out according to the method described in M. Imai et al., Molecular Crystals and Liquid Crystals, Vol. 259, p. 37 (1995). A sample was put into a TN device in which a twist angle was 0 degrees and a distance (cell gap) between two glass substrates was 5 micrometers. A voltage was stepwise applied to the device in the range of 16 V to 19.5 V at an increment of 0.5 V. After 0.2 second with no voltage, a voltage was repeatedly applied under the conditions of only one rectangular wave (rectangular pulse; 0.2 second) and no voltage (2 seconds). A peak current and a peak time of a transient current generated by the applied voltage were measured. A value of rotational viscosity was obtained from the measured values and a calculation equation (8) described in page 40 of the paper presented by M. Imai et al. The dielectric anisotropy value required for the calculation was obtained using the device in which the rotation viscosity was measured and calculating by the method described below.

Optical anisotropy (refractive index anisotropy; Δn; measured at 25° C.): Measurement was carried out by an Abbe refractometer with a polarizing plate mounted on an ocular, using light at a wavelength of 589 nanometers. A surface of a main prism was rubbed in one direction, and then a sample was added dropwise onto the main prism. A refractive index (n∥) was measured when the direction of polarized light was parallel to the direction of rubbing. A refractive index (n⊥) was measured when the direction of polarized light was perpendicular to the direction of rubbing. A value of optical anisotropy was calculated from an equation: Δn=n∥−n⊥.

Dielectric anisotropy (Δ∈; measured at 25° C.): A sample was put in a TN device in which a distance (cell gap) between two glass substrates was 9 micrometers and a twist angle was 80 degrees. Sine waves (10 V, 1 kHz) were applied to the device, and after 2 seconds, a dielectric constant (∈∥) in the major axis direction of liquid crystal molecules was measured. Sine waves (0.5 V, 1 kHz) were applied to the device, and after 2 seconds, a dielectric constant (∈⊥) in the minor axis direction of the liquid crystal molecules was measured. A value of dielectric anisotropy was calculated from an equation: Δ∈=∈∥−∈⊥.

Threshold voltage (Vth; measured at 25° C.; V): An LCD-5100 luminance meter made by Otsuka Electronics Co., Ltd. was used for measurement. A light source was a halogen lamp. A sample was put in a normally white mode TN device in which a distance (cell gap) between two glass substrates was 0.45/Δn (μm) and a twist angle was 80 degrees. A voltage (32 Hz, rectangular waves) to be applied to the device was stepwise increased from 0 V to 10 V at an increment of 0.02 V. On the occasion, the device was irradiated with light from a direction perpendicular to the device, and the amount of light transmitted through the device was measured. A voltage-transmittance curve was prepared, in which a maximum amount of light corresponded to 100% transmittance and a minimum amount of light corresponded to 0% transmittance. A threshold voltage is a voltage at 90% transmittance.

Voltage holding ratio (VHR-1; at 25° C.; %): A TN device used for measurement had a polyimide alignment film, and a distance (cell gap) between two glass substrates was 5 micrometers. A sample was put in the device, and then the device was sealed with an ultraviolet-curable adhesive. A pulse voltage (60 microseconds at 5 V) was applied to the device and the device was charged. A decaying voltage was measured for 16.7 milliseconds with a high-speed voltmeter, and area A between a voltage curve and a horizontal axis in a unit cycle was determined. Area B is an area without decay. A voltage holding ratio is a percentage of area A to area B.

Voltage holding ratio (VHR-2; measured at 80° C.; %): A TN device used for measurement had a polyimide alignment film, and a distance (cell gap) between two glass substrates was 5 micrometers. A sample was put in the device, and then the device was sealed with an ultraviolet-curable adhesive. A pulse voltage (60 microseconds at 5 V) was applied to the TN device and the device was charged. A decaying voltage was measured for 16.7 milliseconds with a high-speed voltmeter, and area A between a voltage curve and a horizontal axis in a unit cycle was determined. Area B is an area without decay. A voltage holding ratio is a percentage of area A to area B.

Voltage holding ratio (VHR-3; measured at 25° C.; %): Stability to ultraviolet light was evaluated by measuring a voltage holding ratio after a device was irradiated with ultraviolet light. A TN device used for measurement had a polyimide alignment film, and a cell gap was 5 micrometers. A sample was injected into the device, and then the device was irradiated with light for 20 minutes. A light source was an ultra high-pressure mercury lamp USH-500D (made by Ushio, Inc.), and a distance between the device and the light source was 20 centimeters. In VHR-3 measurement, a decaying voltage was measured for 16.7 milliseconds. A composition having a large VHR-3 has a large stability to ultraviolet light. A value of VHR-3 is preferably 90% or more, and further preferably, 95% or more.

Voltage holding ratio (VHR-4; measured at 25° C.; %): A TN device into which a sample was injected was heated in a constant-temperature bath at 80° C. for 500 hours, and then stability to heat was evaluated by measuring a voltage holding ratio. In VHR-4 measurement, a decaying voltage was measured for 16.7 milliseconds. A composition having a large VHR-4 has a large stability to heat.

Response time (τ; measured at 25° C.; ms): An LCD-5100 luminance meter made by Otsuka Electronics Co., Ltd. was used for measurement. A light source was a halogen lamp. A low-pass filter was set at 5 kHz. A sample was put in a normally white mode TNA device in which a distance (cell gap) between two glass substrates was 5.0 micrometers and a twist angle was 80 degrees. Rectangular waves (60 Hz, 5 V, 0.5 second) were applied to the device. On the occasion, the device was irradiated with light from a direction perpendicular to the device, and an amount of light transmitted through the device was measured. A maximum amount of light corresponds to 100% transmittance, and a minimum amount of light corresponds to 0% transmittance. Rise time (τr; millisecond) is a period of time needed for change from 90% transmittance to 10% transmittance. Fall time (τf; millisecond) is a period of time needed for 10% transmittance to 90% transmittance. A response time is a sum of rise time and fall time thus obtained.

Elastic constant (K; measured at 25° C.; pN): HP4284A LCR Meter made by Yokogawa-Hewlett-Packard Co. was used for measurement. A sample was put in a horizontal alignment cell in which a distance between two glass substrates (cell gap) was 20 micrometers. An electric charge of 0 V to 20 V was applied to the cell, and electrostatic capacity and applied voltage were measured. The measured values of the electrostatic capacity (C) and the applied voltage (V) were fitted to equation (2.98) and equation (2.101) in page 75 of the “Liquid Crystal Device Handbook” (Ekisho Debaisu Handobukku, in Japanese; The Nikkan Kogyo Shimbun, Ltd.) and a value of K11 and K33 was obtained from equation (2.99). Next, K22 was calculated using the previously determined values of K11 and K33 in formula (3.18) on page 171. An elastic constant is a mean value of K11, K22 and K33 thus obtained.

Specific resistance (ρ; measured at 25° C.; Ωcm): Into a vessel equipped with electrodes, 1.0 milliliter of a sample was injected. A DC voltage (10 V) was applied to the vessel, and a DC current after 10 seconds was measured. A specific resistance was calculated from the following equation: (specific resistance)={(voltage)×(electric capacity of a vessel)}/{(direct current)×(dielectric constant of vacuum)}.

Helical pitch (P; measured at room temperature; μm): A helical pitch was measured according to a wedge method (Handbook of Liquid Crystals (Ekisho Binran in Japanese), page 196, (issued in 2000, Maruzen Co., Ltd.)). A sample was injected into a wedge cell and left to stand at room temperature for 2 hours, and then a gap (d2−d1) between disclination lines was observed by a polarizing microscope (trade name: MM40/60 series, Nikon Corporation). A helical pitch (P) was calculated according to the following equation in which an angle of the wedge cell was expressed as θ: P=2×(d2−d1)×tan θ.

Gas Chromatographic Analysis: GC-14B Gas Chromatograph made by Shimadzu Corporation was used for measurement. A carrier gas was helium (2 mL per minute). A sample injector and a detector (FID) were set to 280° C. and 300° C., respectively. A capillary column DB-1 (length 30 m, bore 0.32 mm, film thickness 0.25 μm; dimethylpolysiloxane as a stationary phase, non-polar) made by Agilent Technologies, Inc. was used for separation of component compounds. After the column was kept at 200° C. for 2 minutes, the column was heated to 280° C. at a rate of 5° C. per minute. A sample was prepared in an acetone solution (0.1% by weight), and then 1 microliter of the solution was injected into the sample injector. A recorder was C-R5A Chromatopac made by Shimadzu Corporation or an equivalent thereof. The resulting chromatogram showed a retention time of a peak and a peak area corresponding to each of the component compounds.

As a solvent for diluting the sample, chloroform, hexane and so forth may also be used. The following capillary columns may also be used for separating the component compounds: HP-1 (length 30 m, bore 0.32 mm, film thickness 0.25 μm) made by Agilent Technologies, Inc., Rtx-1 (length 30 m, bore 0.32 mm, film thickness 0.25 μm) made by Restek Corporation and BP-1 (length 30 m, bore 0.32 mm, film thickness 0.25 μm) made by SGE International Pty. Ltd. A capillary column CBP1-M50-025 (length 50 m, bore 0.25 mm, film thickness 0.25 μm) made by Shimadzu Corporation may also be used for the purpose of avoiding an overlap of peaks of the compounds.

A ratio of liquid crystal compounds contained in the composition may be calculated by the method as described below. The liquid crystal compounds can be detected by a gas chromatograph. A ratio of peak areas in a gas chromatogram corresponds to a ratio (in the number of moles) of the liquid crystal compounds. When the capillary columns described above were used, a correction coefficient of each of the liquid crystal compounds may be regarded as 1 (one). Accordingly, a ratio (% by weight) of the liquid crystal compounds was calculated from the ratio of the peak areas.

The invention will be described in detail by way of Examples. The invention is not limited by the Examples described below. The compounds in Comparative Examples and Examples were described using symbols according to definitions in Table 3 below. In Table 3, a configuration of 1,4-cyclohexylene is trans. A parenthesized number next to a symbolized compound corresponds to the number of the compound. A symbol (-) means any other liquid crystal compound. A ratio (percentage) of the liquid crystal compounds is expressed in terms of weight percent (% by weight) based on the total weight of the liquid crystal composition. The liquid crystal composition includes an impurity. Values of characteristics of the composition were summarized in the last part.

TABLE 3 Method for Description of Compounds using Symbols R—(A₁)—Z₁— . . . —Z_(n)—(A_(n))—R′ Symbol 1) Left-terminal Group R— C_(n)H_(2n+1)— n- C_(n)H_(2n+1)O— nO— C_(m)H_(2m+1)OC_(n)H_(2n)— mOn- CH₂═CH— V— C_(n)H_(2n+1)—CH═CH— nV— CH₂═CH—C_(n)H_(2n)— Vn- C_(m)H_(2m+1)—CH═CH—C_(n)H_(2n)— mVn- CF₂═CH— VFF— CF₂═CH—C_(n)H_(2n)— VFFn- 2) Right-terminal Group —R′ —C_(n)H_(2n+1) -n —OC_(n)H_(2n+1) —On —CH═CH₂ —V —CH═CH—C_(n)H_(2n+1) —Vn —C_(n)H_(2n)—CH═CH₂ -nV —C_(m)H_(2m)—CH═CH—C_(n)H_(2n+1) -mVn —CH═CF₂ —VFF —F —F —Cl —CL —OCF₃ —OCF3 —CF₃ —CF3 3) Bonding Group —Z_(n)— —C₂H₄— 2 —COO— E —CH═CH— V —CH₂O— 1O —OCH₂— O1 —CF₂O— X —C≡C— T 4) Ring Structure —A_(n)—

H

B

B(F)

B(2F)

B(F,F)

B(2F,5F)

Py

G

dh 5) Examples of Description

Example 1

3-GB(F,F)XB(F,F)-F (1-1-1) 6% 3-HH-V (2-1-1) 34%  3-HH-V1 (2-1-1) 10%  V2-HHB-1 (2-5-1) 10%  3-BB(F,F)XB(F,F)-F (3-3-1) 5% 3-HBBXB(F,F)-F (3-5-1) 6% 3-HBB(F,F)XB(F,F)-F (3-6-1) 6% 4-GB(F)B(F,F)XB(F,F)-F (3-8-1) 6% 3-BB(F)B(F,F)XB(F,F)-F (3-9-1) 3% 4-BB(F)B(F,F)XB(F,F)-F (3-9-1) 8% 5-BB(F)B(F,F)XB(F,F)-F (3-9-1) 6% NI = 81.9° C.; Tc < −20° C.; η = 14.8 mPa · s; Δn = 0.106; Δ∈ = 11.7; Vth = 1.23 V.

Comparative Example 1

A liquid crystal composition was formulated in which the compound of the first component of the invention was replaced by compound (3) described in a composition example in WO 96/11897 A in the composition in Example 1. The composition was prepared and measured according to the method described above. Components and characteristics of the composition are as described below.

3-HBXB(F,F)-F (3) 6% 3-HH-V (2-1-1) 34%  3-HH-V1 (2-1-1) 10%  V2-HHB-1 (2-5-1) 10%  3-BB(F,F)XB(F,F)-F (3-3-1) 5% 3-HBBXB(F,F)-F (3-5-1) 6% 3-HBB(F,F)XB(F,F)-F (3-6-1) 6% 4-GB(F)B(F,F)XB(F,F)-F (3-8-1) 6% 3-BB(F)B(F,F)XB(F,F)-F (3-9-1) 3% 4-BB(F)B(F,F)XB(F,F)-F (3-9-1) 8% 5-BB(F)B(F,F)XB(F,F)-F (3-9-1) 6% NI = 83.8° C.; Tc < −20° C.; η = 14.7 mPa · s; Δn = 0.106; Δ∈ = 10.5; Vth = 1.35 V.

The composition in Comparative Example 1 has a smaller dielectric anisotropy in comparison with the composition in Example 1.

Example 2

3-GB(F,F)XB(F,F)-F (1-1-1) 5% 3-HH-V (2-1-1) 6% V-HHB-1 (2-5-1) 10%  3-HHB-1 (2-5-1) 3% 3-HHB-O1 (2-5-1) 4% 3-BBXB(F,F)-F (3-2-1) 5% 3-BB(F,F)XB(F,F)-F (3-3-1) 13%  1-HHXB(F,F)-F (3-4-1) 12%  3-HHXB(F,F)-F (3-4-1) 25%  3-BB(F)B(F,F)XB(F,F)-F (3-9-1) 3% 4-BB(F)B(F,F)XB(F,F)-F (3-9-1) 9% 5-BB(F)B(F,F)XB(F,F)-F (3-9-1) 5% NI = 81.8° C.; Tc < −20° C.; η = 24.2 mPa · s; Δn = 0.110; Δ∈ = 16.7; Vth = 1.07 V.

Example 3

3-GB(F,F)XB(F,F)-F (1-1-1) 4% 5-GB(F,F)XB(F,F)-F (1-1-1) 3% 3-HH-V (2-1-1) 11%  V-HHB-1 (2-5-1) 6% 2-BB(F)B-3 (2-8-1) 3% 5-HBB(F)B-2 (2-13-1) 4% 3-BB(F,F)XB(F,F)-F (3-3-1) 12%  3-HHXB(F,F)-F (3-4-1) 16%  3-HHB(F,F)XB(F,F)-F (3-7-1) 3% 3-BB(F)B(F,F)XB(F,F)-F (3-9-1) 3% 4-BB(F)B(F,F)XB(F,F)-F (3-9-1) 8% 5-BB(F)B(F,F)XB(F,F)-F (3-9-1) 4% 3-BB(F)B(F,F)XB(F)-F (3-9-2) 3% 5-HHB(F,F)-F (3-11-1) 5% 3-HBB(F,F)-F (3-12-1) 15%  NI = 81.6° C.; Tc < −20° C.; η = 28.8 mPa · s; Δn = 0.129; Δ∈ = 15.6; Vth = 1.18 V.

Example 4

3-GB(F,F)XB(F,F)-F (1-1-1) 6% 3-GB(F,F)XB(F)-OCF3 (1-1-2) 5% 3-HH-V (2-1-1) 22%  3-HB-O2 (2-2-1) 6% l-BB-3 (2-3-1) 5% V-HHB-1 (2-5-1) 7% 3-HBB-2 (2-6-1) 3% 3-HHEBH-3 (2-9-1) 3% 3-BB(F,F)XB(F,F)-F (3-3-1) 5% 3-HBBXB(F,F)-F (3-5-1) 6% 3-HBB(F,F)XB(F,F)-F (3-6-1) 6% 4-GB(F)B(F,F)XB(F,F)-F (3-8-1) 5% 4-BB(F)B(F,F)XB(F,F)-F (3-9-1) 8% 5-BB(F)B(F,F)XB(F,F)-F (3-9-1) 6% 3-GHB(F,F)-F (3-13-1) 3% 3-HHEB(F,F)-F (3-14-1) 4% NI = 76.2° C.; Tc < −20° C.; η = 22.8 mPa · s; Δn = 0.113; Δ∈ = 13.1; Vth = 1.16 V.

Example 5

3-GB(F,F)XB(F,F)-F (1-1-1) 6% 5-GB(F,F)XB(F,F)-F (1-1-1) 3% 3-HH-V (2-1-1) 28%  3-HH-V1 (2-1-1) 6% V2-HHB-1 (2-5-1) 12%  3-HB(F)HH-5 (2-10-1) 3% 3-HBBXB(F,F)-F (3-5-1) 6% 3-HBB(F,F)XB(F,F)-F (3-6-1) 6% 4-GB(F)B(F,F)XB(F,F)-F (3-8-1) 6% 3-BB(F)B(F,F)XB(F,F)-F (3-9-1) 3% 4-BB(F)B(F,F)XB(F,F)-F (3-9-1) 7% 5-BB(F)B(F,F)XB(F,F)-F (3-9-1) 4% 3-BB(F)B(F,F)-CF3 (3-15-2) 7% 3-HHBB(F,F)-F (3-16-1) 3% NI = 91.0° C.; Tc < −20° C.; η = 22.3 mPa · s; Δn = 0.117; Δ∈ = 13.3; Vth = 1.25 V.

Example 6

3-GB(F,F)XB(F,F)-F (1-1-1) 5% 3-HH-4 (2-1-1) 6% 3-HH-O1 (2-1-1) 3% 7-HB-1 (2-2-1) 3% V-HHB-1 (2-5-1) 6% 3-HHB-O1 (2-5-1) 4% 5-B(F)BB-2 (2-7-1) 3% 5-HBBH-3 (2-11-1) 3% 3-BB(F,F)XB(F,F)-F (3-3-1) 10%  1-HHXB(F,F)-F (3-4-1) 7% 3-HHXB(F,F)-F (3-4-1) 20%  4-HBB(F,F)XB(F,F)-F (3-6-1) 6% 4-GB(F)B(F,F)XB(F,F)-F (3-8-1) 4% 3-BB(F)B(F,F)XB(F,F)-F (3-9-1) 3% 4-BB(F)B(F,F)XB(F,F)-F (3-9-1) 9% 5-BB(F)B(F,F)XB(F,F)-F (3-9-1) 4% 3-BB(F)B(F,F)XB(F)-F (3-9-2) 4% NI = 88.2° C.; Tc < −20° C.; η = 29.5 mPa · s; Δn = 0.119; Δ∈ = 17.3; Vth = 1.10 V.

Example 7

3-GB(F,F)XB(F,F)-F (1-1-1) 6% 3-HH-V (2-1-1) 20%  3-HH-V1 (2-1-1) 8% 3-HH-VFF (2-1) 3% V2-BB-1 (2-3-1) 3% 3-HHEH-5 (2-4-1) 4% V2-HHB-1 (2-5-1) 4% 3-HB(F)BH-3 (2-12-1) 3% 3-BBXB(F,F)-F (3-2-1) 3% 3-BB(F,F)XB(F)-OCF3 (3-3-2) 3% 5-HBBXB(F,F)-F (3-5-1) 4% 3-HBB(F,F)XB(F,F)-F (3-6-1) 6% 4-GB(F)B(F,F)XB(F,F)-F (3-8-1) 5% 3-BB(F)B(F,F)XB(F,F)-F (3-9-1) 3% 4-BB(F)B(F,F)XB(F,F)-F (3-9-1) 8% 5-BB(F)B(F,F)XB(F,F)-F (3-9-1) 3% 3-HB-CL (3-10-1) 5% 3-BB(F)B(F,F)-F (3-15-1) 6% 1O1-HBBH-3 (—) 3% NI = 81.9° C.; Tc < −20° C.; η = 19.8 mPa · s; Δn = 0.118; Δ∈ = 11.8; Vth = 1.22 V.

Example 8

3-GB(F,F)XB(F,F)-F (1-1-1) 7% 5-GB(F,F)XB(F,F)-F (1-1-1) 4% 3-HH-V (2-1-1) 11%  5-HH-V (2-1-1) 3% V-HHB-1 (2-5-1) 5% 1-BB(F)B-2V (2-8-1) 3% 5-HBB(F)B-2 (2-13-1) 4% 5-HXB(F,F)-F (3-1-1) 3% 3-BB(F,F)XB(F,F)-F (3-3-1) 8% 1-HHXB(F,F)-F (3-4-1) 5% 3-HHXB(F,F)-F (3-4-1) 14%  3-HBBXB(F,F)-F (3-5-1) 4% 5-HBB(F,F)XB(F,F)-F (3-6-1) 3% 5-GB(F)B(F,F)XB(F,F)-F (3-8-1) 5% 3-BB(F)B(F,F)XB(F,F)-F (3-9-1) 3% 4-BB(F)B(F,F)XB(F,F)-F (3-9-1) 8% 5-BB(F)B(F,F)XB(F,F)-F (3-9-1) 4% 3-HBB(F,F)-F (3-12-1) 6% NI = 82.4° C.; Tc < −20° C.; η = 28.8 mPa ·s; Δn = 0.119; Δ∈ = 16.8; Vth = 1.13 V.

The compositions in Examples 1 to 8 have a larger dielectric anisotropy in comparison with the composition in Comparative Example 1. Therefore, the liquid crystal composition of the invention has excellent characteristics.

INDUSTRIAL APPLICABILITY

The invention concerns a liquid crystal composition satisfying at least one of characteristics such as a high maximum temperature of a nematic phase, a low minimum temperature of the nematic phase, a small viscosity, a suitable optical anisotropy, a large dielectric anisotropy, a large specific resistance, a large elastic constant, a high stability to ultraviolet light and a high stability to heat, or a liquid crystal composition having a suitable balance regarding at least two of the characteristics. A liquid crystal display device including such a composition is applied to constitute an AM device having a short response time, a large voltage holding ratio, a large contrast ratio, a long service life and so forth, and thus can be used for a liquid crystal projector, a liquid crystal television and so forth. 

What is claimed is:
 1. A liquid crystal composition having a nematic phase and containing at least one compound represented by formula (1-1-1) as a first component and at least one compound represented by formula (2) as a second component:

wherein R⁵ is straight-chain alkyl having 1 to 12 carbons or straight-chain alkenyl having 2 to 12 carbons; R² and R³ are independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12 carbons in which at least one of hydrogen is replaced by fluorine; ring A and ring B are independently 1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene or 2,5-difluoro-1,4-phenylene; Z² is independently a single bond, ethylene or carbonyloxy; and m is 1, 2 or
 3. 2. The liquid crystal composition according to claim 1, wherein a ratio of the first component is in the range of 5% by weight to 30% by weight based on the total weight of the liquid crystal composition.
 3. The liquid crystal composition according to claim 1, containing at least one compound selected from group of compounds represented by formula (2-1) to formula (2-13) as the second component:

wherein, R² and R³ are independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12 carbons in which at least one of hydrogen is replaced by fluorine.
 4. The liquid crystal composition according to claim 1, wherein a ratio of the second component is in the range of 10% by weight to 80% by weight based on the total weight of the liquid crystal composition.
 5. The liquid crystal composition according to claim 1, further containing at least one compound represented by formula (3) as a third component:

wherein, R⁴ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons; ring C is independently 1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene, 3,5-difluoro-1,4-phenylene, pyrimidine-2,5-diyl, 1,3-dioxane-2,5-diyl or tetrahydropyran-2,5-diyl; X⁵ and X⁶ are independently hydrogen or fluorine; Y² is fluorine, chlorine, trifluoromethyl or trifluoromethoxy; Z³ is independently a single bond, ethylene, carbonyloxy or difluoromethyleneoxy; n is 1, 2 or 3; and when n is 2 and at least one of Z³ is difluoromethyleneoxy, ring C is independently 1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene, 3,5-difluoro-1,4-phenylene, pyrimidine-2,5-diyl or tetrahydropyran-2,5-diyl.
 6. The liquid crystal composition according to claim 5, containing at least one compound selected from the group of compounds represented by formula (3-1) to formula (3-16) as the third component:

wherein, R⁴ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons; X⁵ and X⁶ are independently hydrogen or fluorine; and Y² is fluorine, chlorine, trifluoromethyl or trifluoromethoxy.
 7. The liquid crystal composition according to claim 5, wherein a ratio of the third component is in the range of 20% by weight to 80% by weight based on the total weight of the liquid crystal composition.
 8. The liquid crystal composition according to claim 1, wherein a maximum temperature of a nematic phase is 70° C. or higher, an optical anisotropy (25° C.) at a wavelength of 589 nanometers is 0.07 or more and a dielectric anisotropy (25° C.) at a frequency of 1 kHz is 2 or more.
 9. A liquid crystal display device including the liquid crystal composition according to claim
 1. 10. The liquid crystal display device according to claim 9, wherein an operating mode in the liquid crystal display device is a TN mode, an ECB mode, an OCB mode, an IPS mode, a PSA mode or an FPA mode, and a driving mode in the liquid crystal display device is an active matrix mode.
 11. A liquid crystal display device comprising the liquid crystal composition according to claim
 1. 